Compressed air braking systems such as those used in tractor trailers and the like are well known. In such systems, an air compressor, typically located proximate the engine in the truck, provides compressed air to the brakes of both the truck and the trailer portions of the tractor trailer. Flexible hoses having glad hand couplings are utilized to provide fluid communication from the truck to the trailer.
Such glad hand couplings comprise generally identical mating connectors. Rubber seals are utilized to provide a substantially leak free connection. To effect mating of the glad hand couplings, the two corresponding connectors are positioned perpendicular to one another with their rubber seals laminarly juxtaposed. With the glad hand couplings so positioned, they are rotated approximately ninety degrees, i.e., into alignment with one another, to compress the rubber seals and lock the two glad hand couplings together. In the locked position, the glad hand seals are pressed tightly together such that compressed air tends to flow through the coupling without leaking from between the seals.
However, contemporary rubber seals exhibit a propensity to deform or swage during the coupling process. Swaging typically occurs as the rubber seals of the two glad hand couplings are slid into laminar juxtaposition. Often, a portion of one seal, typically the aperture thereof, will engage the periphery of the opposite seal and cause the engaged portion thereof to roll or curl back toward the center of the seal. Such curling or deformation of the seal, known as swaging, both increases the likelihood of a leak occurring and structurally weakens or damages the seal. The likelihood of a leak occurring is increased since the curled portion of the seal prevents proper mating of the two glad hand seals and tends to provide a path for air leakage therealong.
The deformed seal may be structurally weakened or damaged, particularly as a consequence of prolonged or repeated deformation, due to excessive stretching of the rubber. This stretching commonly results in cracking or tearing of the seal, thus contributing to its tendency to leak.
The propensity for swaging of contemporary glad hand rubber seals is enhanced by the sharply angled, thin peripheral edge portion of the rubber seal. The sharply angled thin periphery of the upper portion of contemporary glad hand seals is very flexible and thus susceptible to being pulled up, away from the glad hand coupling, such that it may fold or curl back toward the bore or opening thereof.
The propensity for contemporary glad hand seals to swage is further enhanced by the sharp, right angle, non-beveled, diameter of the bore at the upper surface of the seal. This sharp, non-beveled diameter tends to engage the outer periphery of the upper surface of an opposing seal during the mating process, thereby pulling it toward the bore thereof as the rubber seals of the two glad hand couplings are brought into laminar juxta position.
Additionally, compressed air braking systems such as those utilized on tractor trailers commonly utilize dual braking systems having both normal and emergency compressed air sources, conduits, and cylinders. Because the compressed air couplings of both normal and emergency compressed air braking systems are identical, there is an ever present potential for incorrectly or cross connecting the two systems such that the emergency air source is in fluid communication with the normal braking system of the trailer and the normal air source is in fluid communication with the emergency braking system of the trailer.
While such cross connecting may not necessarily present an immediate hazard, it does have potential drawbacks. For example, such improper connection could potentially lead to cross-contamination of the two, i.e., normal and emergency, braking systems in the event that one of the systems should become contaminated with dirt, oil, or some other undesirable material.
Furthermore, in some instances the normal and emergency compressed air braking systems may not comprise identical components, i.e. compressed air sources, conduits, and/or cylinders. The compressor of the emergency system may not be designed for use with the cylinders of the normal systems, for example. Thus, inadvertent cross oonnection may result in suboptimal performance of the tractor trailer's braking system.
As such, it is generally considered undesirable to improperly hook up or cross connect the normal and emergency compressed air braking systems. However, it is generally not desirable to form the normal and emergency glad hand couplings such that they cannot be cross connected because such cross connecting is occasionally necessary. This might occur, for instance, if a malfunction occurred in the air source for the normal system and a separate malfunction occurred in the emergency braking system of the trailer. The occurrence of two such malfunctions would render both the normal and the emergency braking systems of the truck inoperative, unless the two braking systems are cross connected to utilize the air source of the emergency braking system with the trailer's normal braking system such that one complete, functioning braking system is provided. Although not a desirable situation, the cross connecting repair does provide an emergency means for continuing operation of the vehicle until a proper repair can be effected.
Thus, although such compressed air systems have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their overall safety and effectiveness. In view of the shortcomings of the prior art, it is desirable to provide an improved seal for glad hand couplings and the like which exhibits a reduced propensity for swaging during the coupling process and which reduces the likelihood of cross connecting.